1. Field of the Invention
The present invention relates to a device controlling the height of a swivel chair which is placed between the seat and the legs of the chair. The present invention more particularly relates to keeping components in place after inserting the components into a piston rod of a cylinder of the device, improving working conditions, and accommodating the operation and rotation of the chair.
2. Description of the Related Art
One example of a device controlling the height of a conventional swivel chair is shown in FIG. 1, an exploded view, and FIG. 2, a cross-sectional view.
A cylinder guide 602 is inserted into a hollow cylindrical outer case 600, and a cylinder 12 is inserted into the cylinder guide 602.
An elastic component 620 is fitted to the end of a piston rod 610 which is placed at the bottom of the cylinder 12. The elastic component 620 absorbs shocks given to the cylinder 12 as the piston rod 610 moves up and down in relation to the cylinder 12. Bearing supports 42 and 44, and a ball bearing component 50 are placed on the end of the piston rod 610.
The bearing supports 42 and 44, and the ball bearing component 50 do not move upward from the end of the piston rod 610 due to a swollen portion 35 which is formed at the piston rod.
A ball bearing 52 is inserted into the ball bearing component 50, and the ball bearing component 50 is sandwiched between the bearing supports 42 and 44 to allow the cylinder 12 to rotate even though weight is applied to the ball bearing component 50 through the body 605 of the cylinder and the elastic body 620.
The bottom of the piston rod 610, which is inserted into the elastic body 602, the ball bearing component 50 and the bearing supports 42 and 44 is placed on a fixer 100 which is extended from the bottom of the outer case 600. The piston rod 610 is fixed to the outer surface of the fixer 100 by inserting a clip 230 into a hole 250 formed in the end of the piston rod 610.
The fixer 100 and the outer case 600 are formed in one body, and the piston rod 610 is fixed to the fixer 100 so that the body 605 of the cylinder 12 can move up and down in the cylinder guide 602 by using a gas or an oil pressure in the cylinder.
The hollow cylindrical outer case is fixed to the base of the chair, and the top of the cylinder 12 is fixed to the seat of the chair so that it is possible to rotate the chair and to control the height of the chair.
The device controlling the height of the conventional swivel chair is already well known to those skilled in this art. The inner structure of the cylinder 12 is described below.
A wall 604 is in contact with the inner surface of the body 605 of the cylinder. An airtight hull/component 606 which includes rings 607 is placed on the top of the wall 604 in order to contain a fluid substance 700 in the chamber of the cylinder without leakage. A piston 608 which moves up and down via the fluid substance 700 is placed at the bottom of the wall 604, and the piston rod 610 is attached to the piston 608.
A button 33 is placed on the top of the airtight hull 606, which is connected with a cock 88 through which the fluid substance 700 enters and exits. Preferably, the cock is formed in the airtight hull 606.
The height-controlling device of the conventional swivel chair described above has the following problem. The components, i.e. the bearing support and the ball bearing component, are easily detached when the piston rod 610 of the cylinder 12 is fixed to the fixer 100 of the outer case 600, resulting in the increase in the manufacturing time.
In order to fix the piston rod 610 of the cylinder 12 to the fixer 100, first, the end of the piston rod 610 is inserted through the elastic body 620, the bearing supports 42 and 44, and the ball bearing component 50, and the cylinder 12 including the piston rod 610 is inserted through the cylinder guide 602 which is inserted into the outer case 600 until the hole 250 which is formed at the end of the piston rod 610 emerges through the fixer 100. The bearing supports 42 and 44, and the ball bearing component are loosely fitted onto the piston rod 610. Therefore, if the piston rod is inserted carelessly, the bearing supports and the ball bearing are detached easily.
In addition, the manufacturing time is increased because the piston rod must be fixed to the fixer slowly and carefully in order to prevent the detachment of the bearing supports and the ball bearing component.
Furthermore, the outer case 600 and the cylinder 12 can be stored separately. When they are stored separately, the bearing supports 42 and 44, and the ball bearing component 50 must also be stored separately with care in order to prevent their loss. This results in added inconvenience.
An objective of the present invention is to eliminate the problems mentioned above, i.e. to prevent the detachment of the elastic body 620, the bearing supports 42 and 44, and the ball bearing component 50.
Another objective of the present invention is to improve work conditions by preventing the detachment of the elastic body 620, the bearing supports 42 and 44, and the ball bearing component 50.
A height-controlling device of a swivel chair according to the present invention is comprised of an elastic body, bearing supports and a ball bearing component which are fitted to the end of a piston rod of a cylinder; and a retaining washer which keeps the elastic body, the bearing supports and the ball bearing in place. The cylinder is inserted into a hollow cylindrical outer case which encloses a cylinder guide. The retaining washer is placed on the inner surface of a fixer of the outer case. The end of the piston rod which emerges from the outer case is fixed on the outer surface of the fixer.
Another height-controlling device of a swivel chair of the present invention is comprised of an elastic body, a bearing support and a thrust bearing which are fitted to the end of a piston rod of a cylinder. In order to prevent detachment of the elastic body, the bearing support and the thrust bearing, the thrust bearing is tightly fitted to the piston rod. The cylinder is inserted into a hollow cylindrical outer case which encloses a cylinder guide. The thrust bearing is placed on the inner surface of a fixer of the outer case, and the end of the piston rod which emerges from the outer case is fixed on the outer surface of the fixer.